1/* 2 * Copyright (C) 1994 Linus Torvalds 3 * 4 * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86 5 * stack - Manfred Spraul <manfred@colorfullife.com> 6 * 7 * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle 8 * them correctly. Now the emulation will be in a 9 * consistent state after stackfaults - Kasper Dupont 10 * <kasperd@daimi.au.dk> 11 * 12 * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont 13 * <kasperd@daimi.au.dk> 14 * 15 * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault 16 * caused by Kasper Dupont's changes - Stas Sergeev 17 * 18 * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes. 19 * Kasper Dupont <kasperd@daimi.au.dk> 20 * 21 * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault. 22 * Kasper Dupont <kasperd@daimi.au.dk> 23 * 24 * 9 apr 2002 - Changed stack access macros to jump to a label 25 * instead of returning to userspace. This simplifies 26 * do_int, and is needed by handle_vm6_fault. Kasper 27 * Dupont <kasperd@daimi.au.dk> 28 * 29 */ 30 31#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 32 33#include <linux/capability.h> 34#include <linux/errno.h> 35#include <linux/interrupt.h> 36#include <linux/syscalls.h> 37#include <linux/sched.h> 38#include <linux/kernel.h> 39#include <linux/signal.h> 40#include <linux/string.h> 41#include <linux/mm.h> 42#include <linux/smp.h> 43#include <linux/highmem.h> 44#include <linux/ptrace.h> 45#include <linux/audit.h> 46#include <linux/stddef.h> 47#include <linux/slab.h> 48#include <linux/security.h> 49 50#include <asm/uaccess.h> 51#include <asm/io.h> 52#include <asm/tlbflush.h> 53#include <asm/irq.h> 54#include <asm/traps.h> 55#include <asm/vm86.h> 56 57/* 58 * Known problems: 59 * 60 * Interrupt handling is not guaranteed: 61 * - a real x86 will disable all interrupts for one instruction 62 * after a "mov ss,xx" to make stack handling atomic even without 63 * the 'lss' instruction. We can't guarantee this in v86 mode, 64 * as the next instruction might result in a page fault or similar. 65 * - a real x86 will have interrupts disabled for one instruction 66 * past the 'sti' that enables them. We don't bother with all the 67 * details yet. 68 * 69 * Let's hope these problems do not actually matter for anything. 70 */ 71 72 73/* 74 * 8- and 16-bit register defines.. 75 */ 76#define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0]) 77#define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1]) 78#define IP(regs) (*(unsigned short *)&((regs)->pt.ip)) 79#define SP(regs) (*(unsigned short *)&((regs)->pt.sp)) 80 81/* 82 * virtual flags (16 and 32-bit versions) 83 */ 84#define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags)) 85#define VEFLAGS (current->thread.vm86->veflags) 86 87#define set_flags(X, new, mask) \ 88((X) = ((X) & ~(mask)) | ((new) & (mask))) 89 90#define SAFE_MASK (0xDD5) 91#define RETURN_MASK (0xDFF) 92 93void save_v86_state(struct kernel_vm86_regs *regs, int retval) 94{ 95 struct tss_struct *tss; 96 struct task_struct *tsk = current; 97 struct vm86plus_struct __user *user; 98 struct vm86 *vm86 = current->thread.vm86; 99 long err = 0; 100 101 /* 102 * This gets called from entry.S with interrupts disabled, but 103 * from process context. Enable interrupts here, before trying 104 * to access user space. 105 */ 106 local_irq_enable(); 107 108 if (!vm86 || !vm86->user_vm86) { 109 pr_alert("no user_vm86: BAD\n"); 110 do_exit(SIGSEGV); 111 } 112 set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->veflags_mask); 113 user = vm86->user_vm86; 114 115 if (!access_ok(VERIFY_WRITE, user, vm86->vm86plus.is_vm86pus ? 116 sizeof(struct vm86plus_struct) : 117 sizeof(struct vm86_struct))) { 118 pr_alert("could not access userspace vm86 info\n"); 119 do_exit(SIGSEGV); 120 } 121 122 put_user_try { 123 put_user_ex(regs->pt.bx, &user->regs.ebx); 124 put_user_ex(regs->pt.cx, &user->regs.ecx); 125 put_user_ex(regs->pt.dx, &user->regs.edx); 126 put_user_ex(regs->pt.si, &user->regs.esi); 127 put_user_ex(regs->pt.di, &user->regs.edi); 128 put_user_ex(regs->pt.bp, &user->regs.ebp); 129 put_user_ex(regs->pt.ax, &user->regs.eax); 130 put_user_ex(regs->pt.ip, &user->regs.eip); 131 put_user_ex(regs->pt.cs, &user->regs.cs); 132 put_user_ex(regs->pt.flags, &user->regs.eflags); 133 put_user_ex(regs->pt.sp, &user->regs.esp); 134 put_user_ex(regs->pt.ss, &user->regs.ss); 135 put_user_ex(regs->es, &user->regs.es); 136 put_user_ex(regs->ds, &user->regs.ds); 137 put_user_ex(regs->fs, &user->regs.fs); 138 put_user_ex(regs->gs, &user->regs.gs); 139 140 put_user_ex(vm86->screen_bitmap, &user->screen_bitmap); 141 } put_user_catch(err); 142 if (err) { 143 pr_alert("could not access userspace vm86 info\n"); 144 do_exit(SIGSEGV); 145 } 146 147 tss = &per_cpu(cpu_tss, get_cpu()); 148 tsk->thread.sp0 = vm86->saved_sp0; 149 tsk->thread.sysenter_cs = __KERNEL_CS; 150 load_sp0(tss, &tsk->thread); 151 vm86->saved_sp0 = 0; 152 put_cpu(); 153 154 memcpy(®s->pt, &vm86->regs32, sizeof(struct pt_regs)); 155 156 lazy_load_gs(vm86->regs32.gs); 157 158 regs->pt.ax = retval; 159} 160 161static void mark_screen_rdonly(struct mm_struct *mm) 162{ 163 pgd_t *pgd; 164 pud_t *pud; 165 pmd_t *pmd; 166 pte_t *pte; 167 spinlock_t *ptl; 168 int i; 169 170 down_write(&mm->mmap_sem); 171 pgd = pgd_offset(mm, 0xA0000); 172 if (pgd_none_or_clear_bad(pgd)) 173 goto out; 174 pud = pud_offset(pgd, 0xA0000); 175 if (pud_none_or_clear_bad(pud)) 176 goto out; 177 pmd = pmd_offset(pud, 0xA0000); 178 split_huge_page_pmd_mm(mm, 0xA0000, pmd); 179 if (pmd_none_or_clear_bad(pmd)) 180 goto out; 181 pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl); 182 for (i = 0; i < 32; i++) { 183 if (pte_present(*pte)) 184 set_pte(pte, pte_wrprotect(*pte)); 185 pte++; 186 } 187 pte_unmap_unlock(pte, ptl); 188out: 189 up_write(&mm->mmap_sem); 190 flush_tlb(); 191} 192 193 194 195static int do_vm86_irq_handling(int subfunction, int irqnumber); 196static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus); 197 198SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86) 199{ 200 return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false); 201} 202 203 204SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg) 205{ 206 switch (cmd) { 207 case VM86_REQUEST_IRQ: 208 case VM86_FREE_IRQ: 209 case VM86_GET_IRQ_BITS: 210 case VM86_GET_AND_RESET_IRQ: 211 return do_vm86_irq_handling(cmd, (int)arg); 212 case VM86_PLUS_INSTALL_CHECK: 213 /* 214 * NOTE: on old vm86 stuff this will return the error 215 * from access_ok(), because the subfunction is 216 * interpreted as (invalid) address to vm86_struct. 217 * So the installation check works. 218 */ 219 return 0; 220 } 221 222 /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */ 223 return do_sys_vm86((struct vm86plus_struct __user *) arg, true); 224} 225 226 227static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus) 228{ 229 struct tss_struct *tss; 230 struct task_struct *tsk = current; 231 struct vm86 *vm86 = tsk->thread.vm86; 232 struct kernel_vm86_regs vm86regs; 233 struct pt_regs *regs = current_pt_regs(); 234 unsigned long err = 0; 235 236 err = security_mmap_addr(0); 237 if (err) { 238 /* 239 * vm86 cannot virtualize the address space, so vm86 users 240 * need to manage the low 1MB themselves using mmap. Given 241 * that BIOS places important data in the first page, vm86 242 * is essentially useless if mmap_min_addr != 0. DOSEMU, 243 * for example, won't even bother trying to use vm86 if it 244 * can't map a page at virtual address 0. 245 * 246 * To reduce the available kernel attack surface, simply 247 * disallow vm86(old) for users who cannot mmap at va 0. 248 * 249 * The implementation of security_mmap_addr will allow 250 * suitably privileged users to map va 0 even if 251 * vm.mmap_min_addr is set above 0, and we want this 252 * behavior for vm86 as well, as it ensures that legacy 253 * tools like vbetool will not fail just because of 254 * vm.mmap_min_addr. 255 */ 256 pr_info_once("Denied a call to vm86(old) from %s[%d] (uid: %d). Set the vm.mmap_min_addr sysctl to 0 and/or adjust LSM mmap_min_addr policy to enable vm86 if you are using a vm86-based DOS emulator.\n", 257 current->comm, task_pid_nr(current), 258 from_kuid_munged(&init_user_ns, current_uid())); 259 return -EPERM; 260 } 261 262 if (!vm86) { 263 if (!(vm86 = kzalloc(sizeof(*vm86), GFP_KERNEL))) 264 return -ENOMEM; 265 tsk->thread.vm86 = vm86; 266 } 267 if (vm86->saved_sp0) 268 return -EPERM; 269 270 if (!access_ok(VERIFY_READ, user_vm86, plus ? 271 sizeof(struct vm86_struct) : 272 sizeof(struct vm86plus_struct))) 273 return -EFAULT; 274 275 memset(&vm86regs, 0, sizeof(vm86regs)); 276 get_user_try { 277 unsigned short seg; 278 get_user_ex(vm86regs.pt.bx, &user_vm86->regs.ebx); 279 get_user_ex(vm86regs.pt.cx, &user_vm86->regs.ecx); 280 get_user_ex(vm86regs.pt.dx, &user_vm86->regs.edx); 281 get_user_ex(vm86regs.pt.si, &user_vm86->regs.esi); 282 get_user_ex(vm86regs.pt.di, &user_vm86->regs.edi); 283 get_user_ex(vm86regs.pt.bp, &user_vm86->regs.ebp); 284 get_user_ex(vm86regs.pt.ax, &user_vm86->regs.eax); 285 get_user_ex(vm86regs.pt.ip, &user_vm86->regs.eip); 286 get_user_ex(seg, &user_vm86->regs.cs); 287 vm86regs.pt.cs = seg; 288 get_user_ex(vm86regs.pt.flags, &user_vm86->regs.eflags); 289 get_user_ex(vm86regs.pt.sp, &user_vm86->regs.esp); 290 get_user_ex(seg, &user_vm86->regs.ss); 291 vm86regs.pt.ss = seg; 292 get_user_ex(vm86regs.es, &user_vm86->regs.es); 293 get_user_ex(vm86regs.ds, &user_vm86->regs.ds); 294 get_user_ex(vm86regs.fs, &user_vm86->regs.fs); 295 get_user_ex(vm86regs.gs, &user_vm86->regs.gs); 296 297 get_user_ex(vm86->flags, &user_vm86->flags); 298 get_user_ex(vm86->screen_bitmap, &user_vm86->screen_bitmap); 299 get_user_ex(vm86->cpu_type, &user_vm86->cpu_type); 300 } get_user_catch(err); 301 if (err) 302 return err; 303 304 if (copy_from_user(&vm86->int_revectored, 305 &user_vm86->int_revectored, 306 sizeof(struct revectored_struct))) 307 return -EFAULT; 308 if (copy_from_user(&vm86->int21_revectored, 309 &user_vm86->int21_revectored, 310 sizeof(struct revectored_struct))) 311 return -EFAULT; 312 if (plus) { 313 if (copy_from_user(&vm86->vm86plus, &user_vm86->vm86plus, 314 sizeof(struct vm86plus_info_struct))) 315 return -EFAULT; 316 vm86->vm86plus.is_vm86pus = 1; 317 } else 318 memset(&vm86->vm86plus, 0, 319 sizeof(struct vm86plus_info_struct)); 320 321 memcpy(&vm86->regs32, regs, sizeof(struct pt_regs)); 322 vm86->user_vm86 = user_vm86; 323 324/* 325 * The flags register is also special: we cannot trust that the user 326 * has set it up safely, so this makes sure interrupt etc flags are 327 * inherited from protected mode. 328 */ 329 VEFLAGS = vm86regs.pt.flags; 330 vm86regs.pt.flags &= SAFE_MASK; 331 vm86regs.pt.flags |= regs->flags & ~SAFE_MASK; 332 vm86regs.pt.flags |= X86_VM_MASK; 333 334 vm86regs.pt.orig_ax = regs->orig_ax; 335 336 switch (vm86->cpu_type) { 337 case CPU_286: 338 vm86->veflags_mask = 0; 339 break; 340 case CPU_386: 341 vm86->veflags_mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL; 342 break; 343 case CPU_486: 344 vm86->veflags_mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 345 break; 346 default: 347 vm86->veflags_mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL; 348 break; 349 } 350 351/* 352 * Save old state 353 */ 354 vm86->saved_sp0 = tsk->thread.sp0; 355 lazy_save_gs(vm86->regs32.gs); 356 357 tss = &per_cpu(cpu_tss, get_cpu()); 358 /* make room for real-mode segments */ 359 tsk->thread.sp0 += 16; 360 if (cpu_has_sep) 361 tsk->thread.sysenter_cs = 0; 362 load_sp0(tss, &tsk->thread); 363 put_cpu(); 364 365 if (vm86->flags & VM86_SCREEN_BITMAP) 366 mark_screen_rdonly(tsk->mm); 367 368 memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs)); 369 force_iret(); 370 return regs->ax; 371} 372 373static inline void set_IF(struct kernel_vm86_regs *regs) 374{ 375 VEFLAGS |= X86_EFLAGS_VIF; 376} 377 378static inline void clear_IF(struct kernel_vm86_regs *regs) 379{ 380 VEFLAGS &= ~X86_EFLAGS_VIF; 381} 382 383static inline void clear_TF(struct kernel_vm86_regs *regs) 384{ 385 regs->pt.flags &= ~X86_EFLAGS_TF; 386} 387 388static inline void clear_AC(struct kernel_vm86_regs *regs) 389{ 390 regs->pt.flags &= ~X86_EFLAGS_AC; 391} 392 393/* 394 * It is correct to call set_IF(regs) from the set_vflags_* 395 * functions. However someone forgot to call clear_IF(regs) 396 * in the opposite case. 397 * After the command sequence CLI PUSHF STI POPF you should 398 * end up with interrupts disabled, but you ended up with 399 * interrupts enabled. 400 * ( I was testing my own changes, but the only bug I 401 * could find was in a function I had not changed. ) 402 * [KD] 403 */ 404 405static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs) 406{ 407 set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask); 408 set_flags(regs->pt.flags, flags, SAFE_MASK); 409 if (flags & X86_EFLAGS_IF) 410 set_IF(regs); 411 else 412 clear_IF(regs); 413} 414 415static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs) 416{ 417 set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask); 418 set_flags(regs->pt.flags, flags, SAFE_MASK); 419 if (flags & X86_EFLAGS_IF) 420 set_IF(regs); 421 else 422 clear_IF(regs); 423} 424 425static inline unsigned long get_vflags(struct kernel_vm86_regs *regs) 426{ 427 unsigned long flags = regs->pt.flags & RETURN_MASK; 428 429 if (VEFLAGS & X86_EFLAGS_VIF) 430 flags |= X86_EFLAGS_IF; 431 flags |= X86_EFLAGS_IOPL; 432 return flags | (VEFLAGS & current->thread.vm86->veflags_mask); 433} 434 435static inline int is_revectored(int nr, struct revectored_struct *bitmap) 436{ 437 __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0" 438 :"=r" (nr) 439 :"m" (*bitmap), "r" (nr)); 440 return nr; 441} 442 443#define val_byte(val, n) (((__u8 *)&val)[n]) 444 445#define pushb(base, ptr, val, err_label) \ 446 do { \ 447 __u8 __val = val; \ 448 ptr--; \ 449 if (put_user(__val, base + ptr) < 0) \ 450 goto err_label; \ 451 } while (0) 452 453#define pushw(base, ptr, val, err_label) \ 454 do { \ 455 __u16 __val = val; \ 456 ptr--; \ 457 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 458 goto err_label; \ 459 ptr--; \ 460 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 461 goto err_label; \ 462 } while (0) 463 464#define pushl(base, ptr, val, err_label) \ 465 do { \ 466 __u32 __val = val; \ 467 ptr--; \ 468 if (put_user(val_byte(__val, 3), base + ptr) < 0) \ 469 goto err_label; \ 470 ptr--; \ 471 if (put_user(val_byte(__val, 2), base + ptr) < 0) \ 472 goto err_label; \ 473 ptr--; \ 474 if (put_user(val_byte(__val, 1), base + ptr) < 0) \ 475 goto err_label; \ 476 ptr--; \ 477 if (put_user(val_byte(__val, 0), base + ptr) < 0) \ 478 goto err_label; \ 479 } while (0) 480 481#define popb(base, ptr, err_label) \ 482 ({ \ 483 __u8 __res; \ 484 if (get_user(__res, base + ptr) < 0) \ 485 goto err_label; \ 486 ptr++; \ 487 __res; \ 488 }) 489 490#define popw(base, ptr, err_label) \ 491 ({ \ 492 __u16 __res; \ 493 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 494 goto err_label; \ 495 ptr++; \ 496 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 497 goto err_label; \ 498 ptr++; \ 499 __res; \ 500 }) 501 502#define popl(base, ptr, err_label) \ 503 ({ \ 504 __u32 __res; \ 505 if (get_user(val_byte(__res, 0), base + ptr) < 0) \ 506 goto err_label; \ 507 ptr++; \ 508 if (get_user(val_byte(__res, 1), base + ptr) < 0) \ 509 goto err_label; \ 510 ptr++; \ 511 if (get_user(val_byte(__res, 2), base + ptr) < 0) \ 512 goto err_label; \ 513 ptr++; \ 514 if (get_user(val_byte(__res, 3), base + ptr) < 0) \ 515 goto err_label; \ 516 ptr++; \ 517 __res; \ 518 }) 519 520/* There are so many possible reasons for this function to return 521 * VM86_INTx, so adding another doesn't bother me. We can expect 522 * userspace programs to be able to handle it. (Getting a problem 523 * in userspace is always better than an Oops anyway.) [KD] 524 */ 525static void do_int(struct kernel_vm86_regs *regs, int i, 526 unsigned char __user *ssp, unsigned short sp) 527{ 528 unsigned long __user *intr_ptr; 529 unsigned long segoffs; 530 struct vm86 *vm86 = current->thread.vm86; 531 532 if (regs->pt.cs == BIOSSEG) 533 goto cannot_handle; 534 if (is_revectored(i, &vm86->int_revectored)) 535 goto cannot_handle; 536 if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored)) 537 goto cannot_handle; 538 intr_ptr = (unsigned long __user *) (i << 2); 539 if (get_user(segoffs, intr_ptr)) 540 goto cannot_handle; 541 if ((segoffs >> 16) == BIOSSEG) 542 goto cannot_handle; 543 pushw(ssp, sp, get_vflags(regs), cannot_handle); 544 pushw(ssp, sp, regs->pt.cs, cannot_handle); 545 pushw(ssp, sp, IP(regs), cannot_handle); 546 regs->pt.cs = segoffs >> 16; 547 SP(regs) -= 6; 548 IP(regs) = segoffs & 0xffff; 549 clear_TF(regs); 550 clear_IF(regs); 551 clear_AC(regs); 552 return; 553 554cannot_handle: 555 save_v86_state(regs, VM86_INTx + (i << 8)); 556} 557 558int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) 559{ 560 struct vm86 *vm86 = current->thread.vm86; 561 562 if (vm86->vm86plus.is_vm86pus) { 563 if ((trapno == 3) || (trapno == 1)) { 564 save_v86_state(regs, VM86_TRAP + (trapno << 8)); 565 return 0; 566 } 567 do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs)); 568 return 0; 569 } 570 if (trapno != 1) 571 return 1; /* we let this handle by the calling routine */ 572 current->thread.trap_nr = trapno; 573 current->thread.error_code = error_code; 574 force_sig(SIGTRAP, current); 575 return 0; 576} 577 578void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) 579{ 580 unsigned char opcode; 581 unsigned char __user *csp; 582 unsigned char __user *ssp; 583 unsigned short ip, sp, orig_flags; 584 int data32, pref_done; 585 struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus; 586 587#define CHECK_IF_IN_TRAP \ 588 if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \ 589 newflags |= X86_EFLAGS_TF 590 591 orig_flags = *(unsigned short *)®s->pt.flags; 592 593 csp = (unsigned char __user *) (regs->pt.cs << 4); 594 ssp = (unsigned char __user *) (regs->pt.ss << 4); 595 sp = SP(regs); 596 ip = IP(regs); 597 598 data32 = 0; 599 pref_done = 0; 600 do { 601 switch (opcode = popb(csp, ip, simulate_sigsegv)) { 602 case 0x66: /* 32-bit data */ data32 = 1; break; 603 case 0x67: /* 32-bit address */ break; 604 case 0x2e: /* CS */ break; 605 case 0x3e: /* DS */ break; 606 case 0x26: /* ES */ break; 607 case 0x36: /* SS */ break; 608 case 0x65: /* GS */ break; 609 case 0x64: /* FS */ break; 610 case 0xf2: /* repnz */ break; 611 case 0xf3: /* rep */ break; 612 default: pref_done = 1; 613 } 614 } while (!pref_done); 615 616 switch (opcode) { 617 618 /* pushf */ 619 case 0x9c: 620 if (data32) { 621 pushl(ssp, sp, get_vflags(regs), simulate_sigsegv); 622 SP(regs) -= 4; 623 } else { 624 pushw(ssp, sp, get_vflags(regs), simulate_sigsegv); 625 SP(regs) -= 2; 626 } 627 IP(regs) = ip; 628 goto vm86_fault_return; 629 630 /* popf */ 631 case 0x9d: 632 { 633 unsigned long newflags; 634 if (data32) { 635 newflags = popl(ssp, sp, simulate_sigsegv); 636 SP(regs) += 4; 637 } else { 638 newflags = popw(ssp, sp, simulate_sigsegv); 639 SP(regs) += 2; 640 } 641 IP(regs) = ip; 642 CHECK_IF_IN_TRAP; 643 if (data32) 644 set_vflags_long(newflags, regs); 645 else 646 set_vflags_short(newflags, regs); 647 648 goto check_vip; 649 } 650 651 /* int xx */ 652 case 0xcd: { 653 int intno = popb(csp, ip, simulate_sigsegv); 654 IP(regs) = ip; 655 if (vmpi->vm86dbg_active) { 656 if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) { 657 save_v86_state(regs, VM86_INTx + (intno << 8)); 658 return; 659 } 660 } 661 do_int(regs, intno, ssp, sp); 662 return; 663 } 664 665 /* iret */ 666 case 0xcf: 667 { 668 unsigned long newip; 669 unsigned long newcs; 670 unsigned long newflags; 671 if (data32) { 672 newip = popl(ssp, sp, simulate_sigsegv); 673 newcs = popl(ssp, sp, simulate_sigsegv); 674 newflags = popl(ssp, sp, simulate_sigsegv); 675 SP(regs) += 12; 676 } else { 677 newip = popw(ssp, sp, simulate_sigsegv); 678 newcs = popw(ssp, sp, simulate_sigsegv); 679 newflags = popw(ssp, sp, simulate_sigsegv); 680 SP(regs) += 6; 681 } 682 IP(regs) = newip; 683 regs->pt.cs = newcs; 684 CHECK_IF_IN_TRAP; 685 if (data32) { 686 set_vflags_long(newflags, regs); 687 } else { 688 set_vflags_short(newflags, regs); 689 } 690 goto check_vip; 691 } 692 693 /* cli */ 694 case 0xfa: 695 IP(regs) = ip; 696 clear_IF(regs); 697 goto vm86_fault_return; 698 699 /* sti */ 700 /* 701 * Damn. This is incorrect: the 'sti' instruction should actually 702 * enable interrupts after the /next/ instruction. Not good. 703 * 704 * Probably needs some horsing around with the TF flag. Aiee.. 705 */ 706 case 0xfb: 707 IP(regs) = ip; 708 set_IF(regs); 709 goto check_vip; 710 711 default: 712 save_v86_state(regs, VM86_UNKNOWN); 713 } 714 715 return; 716 717check_vip: 718 if (VEFLAGS & X86_EFLAGS_VIP) { 719 save_v86_state(regs, VM86_STI); 720 return; 721 } 722 723vm86_fault_return: 724 if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) { 725 save_v86_state(regs, VM86_PICRETURN); 726 return; 727 } 728 if (orig_flags & X86_EFLAGS_TF) 729 handle_vm86_trap(regs, 0, X86_TRAP_DB); 730 return; 731 732simulate_sigsegv: 733 /* FIXME: After a long discussion with Stas we finally 734 * agreed, that this is wrong. Here we should 735 * really send a SIGSEGV to the user program. 736 * But how do we create the correct context? We 737 * are inside a general protection fault handler 738 * and has just returned from a page fault handler. 739 * The correct context for the signal handler 740 * should be a mixture of the two, but how do we 741 * get the information? [KD] 742 */ 743 save_v86_state(regs, VM86_UNKNOWN); 744} 745 746/* ---------------- vm86 special IRQ passing stuff ----------------- */ 747 748#define VM86_IRQNAME "vm86irq" 749 750static struct vm86_irqs { 751 struct task_struct *tsk; 752 int sig; 753} vm86_irqs[16]; 754 755static DEFINE_SPINLOCK(irqbits_lock); 756static int irqbits; 757 758#define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \ 759 | (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \ 760 | (1 << SIGUNUSED)) 761 762static irqreturn_t irq_handler(int intno, void *dev_id) 763{ 764 int irq_bit; 765 unsigned long flags; 766 767 spin_lock_irqsave(&irqbits_lock, flags); 768 irq_bit = 1 << intno; 769 if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk) 770 goto out; 771 irqbits |= irq_bit; 772 if (vm86_irqs[intno].sig) 773 send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1); 774 /* 775 * IRQ will be re-enabled when user asks for the irq (whether 776 * polling or as a result of the signal) 777 */ 778 disable_irq_nosync(intno); 779 spin_unlock_irqrestore(&irqbits_lock, flags); 780 return IRQ_HANDLED; 781 782out: 783 spin_unlock_irqrestore(&irqbits_lock, flags); 784 return IRQ_NONE; 785} 786 787static inline void free_vm86_irq(int irqnumber) 788{ 789 unsigned long flags; 790 791 free_irq(irqnumber, NULL); 792 vm86_irqs[irqnumber].tsk = NULL; 793 794 spin_lock_irqsave(&irqbits_lock, flags); 795 irqbits &= ~(1 << irqnumber); 796 spin_unlock_irqrestore(&irqbits_lock, flags); 797} 798 799void release_vm86_irqs(struct task_struct *task) 800{ 801 int i; 802 for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++) 803 if (vm86_irqs[i].tsk == task) 804 free_vm86_irq(i); 805} 806 807static inline int get_and_reset_irq(int irqnumber) 808{ 809 int bit; 810 unsigned long flags; 811 int ret = 0; 812 813 if (invalid_vm86_irq(irqnumber)) return 0; 814 if (vm86_irqs[irqnumber].tsk != current) return 0; 815 spin_lock_irqsave(&irqbits_lock, flags); 816 bit = irqbits & (1 << irqnumber); 817 irqbits &= ~bit; 818 if (bit) { 819 enable_irq(irqnumber); 820 ret = 1; 821 } 822 823 spin_unlock_irqrestore(&irqbits_lock, flags); 824 return ret; 825} 826 827 828static int do_vm86_irq_handling(int subfunction, int irqnumber) 829{ 830 int ret; 831 switch (subfunction) { 832 case VM86_GET_AND_RESET_IRQ: { 833 return get_and_reset_irq(irqnumber); 834 } 835 case VM86_GET_IRQ_BITS: { 836 return irqbits; 837 } 838 case VM86_REQUEST_IRQ: { 839 int sig = irqnumber >> 8; 840 int irq = irqnumber & 255; 841 if (!capable(CAP_SYS_ADMIN)) return -EPERM; 842 if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM; 843 if (invalid_vm86_irq(irq)) return -EPERM; 844 if (vm86_irqs[irq].tsk) return -EPERM; 845 ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL); 846 if (ret) return ret; 847 vm86_irqs[irq].sig = sig; 848 vm86_irqs[irq].tsk = current; 849 return irq; 850 } 851 case VM86_FREE_IRQ: { 852 if (invalid_vm86_irq(irqnumber)) return -EPERM; 853 if (!vm86_irqs[irqnumber].tsk) return 0; 854 if (vm86_irqs[irqnumber].tsk != current) return -EPERM; 855 free_vm86_irq(irqnumber); 856 return 0; 857 } 858 } 859 return -EINVAL; 860} 861 862